Cushing syndrome due to ACTH-secreting pheochromocytoma, aggravated by glucocorticoid-driven positive-feedback loop

Ikki Sakuma, Seiichiro Higuchi, Masanori Fujimoto, Tomoko Takiguchi, Akitoshi Nakayama, Ai Tamura, Takashi Kohno, Eri Komai, Akina Shiga, Hidekazu Nagano, Naoko Hashimoto, Sawako Suzuki, Takafumi Mayama, Hisashi Koide, Katsuhiko Ono, Hironobu Sasano, Ichiro Tatsuno, Koutaro Yokote, Tomoaki Tanaka

研究成果: Article査読

23 被引用数 (Scopus)


Context: Pheochromocytoma is a catecholamine-producing tumor that originates from adrenal chromaffin cells and is capable of secreting various hormones, including ACTH. Case Description: A 56-year-old female presented with Cushingoid appearance and diabetic ketoacidosis. Endocrinological examinations demonstrated ectopic ACTH production with hypercortisolemia and excess urinary cortisol accompanied by elevated plasma and urine catecholamines. Computed tomography revealed a large left adrenal tumor with bilateral adrenal enlargement. Metaiodobenzylguanidine scintigraphy revealed abnormal accumulation in the tumor, which was eventually diagnosed as pheochromocytoma with ectopic ACTH secretion with subsequent manifestation of Cushing's syndrome. Ectopic ACTH secretion and catecholamine production were blocked by metyrapone treatment, whereas dexamethasone paradoxically increased ACTH secretion. Left adrenalectomy resulted in complete remission of Cushing's syndrome and pheochromocytoma. In Vitro Studies: Immunohistological analysis revealed that the tumor contained two functionally distinct chromaffin-like cell types. The majority of tumor cells stained positive for tyrosine hydroxylase (TH), whereas a minor population of ACTH-positive tumor cells was negative for TH. Furthermore, gene expression and in vitro functional analyses using primary tumor tissue cultures demonstrated that dexamethasone facilitated ACTH as well as catecholamine secretion with parallel induction of proopiomelanocortin (POMC), TH, and phenylethanolamine N-methyltransferase mRNA, supporting a glucocorticoid-dependent positive-feedback loop of ACTH secretion in vivo. DNA methylation analysis revealed that the POMC promoter of this tumor, particularly the E2F binding site, was hypomethylated. Conclusion: We present a case of ectopic ACTH syndrome associated with pheochromocytoma. ACTH up-regulation with paradoxical response to glucocorticoid, possibly through the hypomethylation of the POMC promoter, exacerbated the patient's condition.

ジャーナルJournal of Clinical Endocrinology and Metabolism
出版ステータスPublished - 2016 3月

ASJC Scopus subject areas

  • 内分泌学、糖尿病および代謝内科学
  • 生化学
  • 内分泌学
  • 臨床生化学
  • 生化学、医学


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